|
Author |
Message |
|
Manager
Status: I will not stop until i realise my goal which is my dream too
Joined: 25 Feb 2010
Posts: 247
Followers: 2
Kudos [?]:
14
[0], given: 16
|
Re: M03 #09 PS : Trains [#permalink]
 28 Mar 2012, 06:10
Quite Simple.... Washington to Baltimore - 120kms A takes 30mph B takes 90mph A at Washington and B at Baltimore at same time at 1st hr, they meet for the first time, A would have covered 30kms from Washington, B 90kms from Baltimore at 2nd hr, they meet again, A would have covered 60kms from Washington, B would have covered 30kms from their first meeting point to Washington and then travels return journey of 60kms to meet at 60Kms point from Washington. So first was at 30kms from Washington and 2nd was at 60kms from Washington...hence the difference is 30kms Hope this is a simple method...but my worry is the more complex problems of this nature....can somebody share such problems?
_________________
Regards,
Harsha
Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat 
Satyameva Jayate - Truth alone triumphs
|
|
|
|
|
|
|
Manager
Joined: 27 Oct 2011
Posts: 196
Location: United States
Concentration: Finance, Strategy
GMAT 1: Q V
GPA: 3.7
WE: Account Management (Consumer Products)
Followers: 1
Kudos [?]:
25
[0], given: 4
|
Re: M03 #09 PS : Trains [#permalink]
28 Mar 2012, 13:33
All great answer. Helped me answer the question better. You must take note that train A has traveled an extra 10 miles after they meet. which is what i forgot.
_________________
DETERMINED TO BREAK 700!!!
|
|
|
|
|
|
Manager
Joined: 28 Apr 2011
Posts: 188
Followers: 0
Kudos [?]:
3
[0], given: 6
|
Re: M03 #09 PS : Trains [#permalink]
28 Mar 2012, 22:00
Sure it is c.....
1 meeting point x/ Speed of A = 120-x /speed of B
gives x=30 miles.
now while B trvaels 30 miles to reach end point with in that 20 min A travels 10 miles.
2. Relative speed in same direction= 90-30=60
now 40/60 = 2/3 hr i.e 40 min
in 40 min B travels 60 Km i.e second meeting pt at 60 miles
so 60-30= 30 miles apart.
|
|
|
|
|
|
Intern
Joined: 28 Jan 2012
Posts: 19
Followers: 0
Kudos [?]:
0
[0], given: 2
|
Re: M03 #09 PS : Trains [#permalink]
29 Mar 2012, 03:26
Easy question!!!  Train speeds: Train A 30mph, Train B 90mph. Total distance is 120 miles. in 1st hour, train A would have travelled 30 miles, train B would have travelled 90 miles. I st hour: Train A ---------> 30 miles <----------------------------- Train B 90 miles Train A and B meet at 30 miles. 2nd hour: train A would have another travelled 30miles, train B would have travelled another 90 miles.(remaining 30 miles and 60 miles on return) Train A --------->------------> 60miles ----------------------> Train B 60miles second time, they meet at 60 miles. Difference in miles between the point they met at first time and second time is 60-30= 30 miles So the answer is B.
|
|
|
|
|
|
Manager
Joined: 28 Oct 2009
Posts: 99
Followers: 1
Kudos [?]:
3
[0], given: 42
|
Re: M03 #09 PS : Trains [#permalink]
29 Mar 2012, 16:41
Is the simpler way to answer the question : t1 = 30/mph t2 =90mph
So 30+90 = 120 = 1 hour.
In one hour train 1 will have traveled 30 mi therefore they would have to meet at 30 mi.
|
|
|
|
|
|
Manager
Joined: 15 Aug 2012
Posts: 50
Location: India
Concentration: Technology, Strategy
GPA: 3.6
WE: General Management (Computer Software)
Followers: 0
Kudos [?]:
7
[0], given: 5
|
Re: M03 #09 PS : Trains [#permalink]
29 Mar 2013, 06:00
Seeing the values:
After 1 hour. The trains meet for the first time. A and B intersect at Point 1
After 1 more hour, the train with 90kmph(B) overtakes 30kmph(A) train at Point 2
(30mph)->A__________1_________2____________________B<-(90mph)
A <-30m-> 1 <-30m-> 2 <-60m-> B
Distance between 1 and 2 is 30 miles.
|
|
|
|
|
|
Manager
Joined: 12 Dec 2012
Posts: 210
Concentration: Leadership, Marketing
GMAT 1: 540 Q36 V28
GMAT 2: 550 Q39 V27
GMAT 3: 620 Q42 V33
GPA: 2.82
WE: Human Resources (Health Care)
Followers: 1
Kudos [?]:
25
[0], given: 168
|
Re: M03 #09 PS : Trains [#permalink]
29 Mar 2013, 16:07
I still cannot understand how to tackle the problem despite I read all the provided explanations . Any body can kindly provide a step -by-step explanation please?
_________________
My RC Recipe
http://gmatclub.com/forum/the-rc-recipe-149577.html
My Problem Takeaway Template
http://gmatclub.com/forum/the-simplest-problem-takeaway-template-150646.html
|
|
|
|
|
|
Intern
Joined: 19 Mar 2013
Posts: 16
Location: Sweden
GPA: 3.78
Followers: 0
Kudos [?]:
8
[1] , given: 15
|
Re: M03 #09 PS : Trains [#permalink]
30 Mar 2013, 01:11
1
This post received
KUDOS
Quick answ:
I also just drev à Quick diagram, working fine for tis question but not for more Advanced train questions.
|
|
|
|
|
|
Intern
Joined: 17 Jan 2013
Posts: 37
Followers: 1
Kudos [?]:
1
[0], given: 67
|
Re: M03 #09 PS : Trains [#permalink]
31 Mar 2013, 09:29
I think i took an easier approach: The relative speed of train B will be 90+30=120 distance 120miles, relative speed for B (assuming A stationary) =120mph time taken =120/120=1 hours Hence they meet after one hour i.e. A has travelled 30miles and B has travelled 90 miles. DC---30----60---90----120 Baltimore We can say for every 30 miles A covers train B covers 90 miles.. after meeting 30miles away from DC: DC---x---60---90---120 Train A goes till 30 miles farther where train B covers 90 kms.. i.e. reaches DC and meets at point 60 miles away from DC Hence they meet now at: DC---X----x---90---120 Clearly we can see distance between two meeting points is 30 miles Hope it helps
|
|
|
|
|
|
Intern
Status: Rotterdam Erasmus; McGill Desautels UBC Sauder - Admitted
Joined: 28 May 2011
Posts: 22
Schools: ISB, INSEAD, Harvard, Warton
Followers: 0
Kudos [?]:
6
[0], given: 10
|
Re: M03 #09 PS : Trains [#permalink]
01 Apr 2013, 00:54
Ans: (B).. Since Train A starts from Washington and Train B from Baltimore, hence they are travelling in opposite direction. So the relative speed = 120 mph (90 + 30).. Total time taken = Total distance / Relative speed => 120 / 120 = 1hr. So the distance travelled by each train is : A - 30 miles ; B - 90 miles. Let this point of first rendevouz be X. Now the catch in the question is that they travel continuously, so there is a possibility that they may meet again while travelling in the same direction.. figure below: Washisngton .............X............Y........... Baltimore 30m 30m 30m Now we can observe that while Train A would had travelled another 30 miles in next 1hr (its speed is 30 mph). So it’s distance from Washington = 60 miles. Train B would had covered the remaining 30 miles from X till Washington and backtracked to the current position of Train A by covering remaining 60m from Washington within 1 hr (train B speed is 90mph). Let this point of second meet be Y. So the distance between Y and X = 60 – 30 = 30 miles
_________________
-- Because beauty Lies in the Eyes.. So donate those eyes
KUDOS if like the post ...
|
|
|
|
|
|
Intern
Joined: 28 Feb 2013
Posts: 13
Followers: 0
Kudos [?]:
1
[0], given: 7
|
Re: M03 #09 PS : Trains [#permalink]
01 Apr 2013, 04:22
For distance =120 and 2 trains at 90+30 mph= 120mph makes it very easy.
For 1st time they will meet at 30miles from Washington..now from this moment we check when will they meet again, again the distance between them is 120 so again train A will meet after 30miles.
|
|
|
|
|
|
Intern
Joined: 27 Oct 2011
Posts: 15
Concentration: Finance, Technology
GMAT Date: 04-10-2012
Followers: 0
Kudos [?]:
3
[0], given: 6
|
Re: M03 #09 PS : Trains [#permalink]
02 Apr 2013, 23:49
(B) 30 miles Total Rate = 90+30 = 120 Distance = 120 Time to meet the trains = 120/120 = 1 Hour.. So in every one hour both trains will meet i.e. After 1 hour Train A reaches to a place C= 30 km from washington After 2 hour Train A reaches to a place D= 60 km from washington, Distance Between C and D = 30 After 3 hour Train A reaches to a place E= 90 km from washington, Distance Between D and E = 30 Do let me know in case there is a hole in the logic nice Question.
|
|
|
|
|
|
|
Re: M03 #09 PS : Trains
[#permalink]
02 Apr 2013, 23:49
|
|
|
|
|
|
|
|
|
|
|
close
